Braintrust co-founder and director Dr Helen Bulbeck said: “It goes against nature to lose a child and I think brain tumours bring their own specific trauma where it robs a person of their very identity.
“The family turned every stone for a different outcome and they held on to every hope, as you should.
“It’s just unimaginable what they are going through.”
In a bid to improve outcomes for others in his situation, Alex met Health Secretary Wes Streeting, who said he had been “struck immediately” by his “courage, clarity and determination”.
He said: “My thoughts are with Alex’s family and loved ones – I want to assure them that I am personally committed to ensuring his legacy is felt in the way we support patients and fund research into the cancers that have for too long been overlooked.”